The invention relates to appliances and devices that are implanted into the body, such as for orthopedic purposes, and that have antimicrobial properties.
Various devices are often implanted into the body of a human or animal for orthopedic purposes such as to strengthen bones, as described in U.S. Pat. No. 5,443,513; fasten portions of a bone to correct a fracture, such as in U.S. Pat. No. 4,632,101; and replace joints such as a hip replacement, such as in U.S. Pat. No. 5,522,904. Other joint replacement applications include the knee and small joints such as the fingers.
Such implants can be of metal, of plastic and of composites, such as carbon fibers in a plastic matrix. The outer exposed surfaces of devices implanted into the body come into contact with body tissue and fluids. Since they are foreign in nature to the body they pose a site for growth of bacteria and potential infection. Therefore, it would be desirable to provide such devices with antimicrobial properties so as to reduce the growth of bacteria and risk of infection or to eliminate these problems.
U.S. Pat. No. 5,756,145 describes the infection problem caused by medical implants, such a replacement hip joints, and seeks to solve the problem by providing the implant with an antimicrobial coating layer that is covered by one or more protective coating layers. The antimicrobial materials considered are basically of a liquid organic type that require a protective coating layer. This increases the complexity of providing the implant with the desired antimicrobial property. Also, consideration has to be given to the durability of the coating and the effectiveness of the antimicrobial action due to the coating.
The present invention relates to devices implantable into the body, such as for orthopaedic purposes, having antimicrobial properties produced by an inorganic antimicrobial agent. In a preferred embodiment of the invention, the agent is a zeolite. In the case of the device being of metal, the agent is incorporated in a coating that is applied to the surface of the device. With the device being of a polymer (plastic) or a composite of fibers and plastic resin, the resin forming the implant includes the agent. In either case the exposed surface of the implant has an inorganic antimicrobial agent that contacts the body tissue or fluids and kills bacteria.
It is therefore an object of the invention to provide an orthopaedic implant device that includes an inorganic antimicrobial agent.
A further object is to provide an orthopaedic implant having an inorganic zeolite on its surface to provide antimicrobial action.
Yet another object is to provide an orthopaedic implant of polymeric resin material including an inorganic antimicrobial agent.
An additional object is to provide an orthopaedic implant of metal having a coating on its surface that contains an inorganic antimicrobial agent.